Improvement in machines for threading screws



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NICHOLAS B. HADLY, OF PROVIDENCE, RHODE ISLAND.

Letters Patent No. 91,117, dated June 8, 1869.

IMPROVEMENT IN MACHINES FOR THREADING- SCREWS.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom 'it may concern:

Be it known that I, NICHOLAS B. HADLEY, of the city and county of Providence, in the State of Rhode Island, have invented certain new and useful Improvements in Machines for Threading Screws; and I do hereby declare that the following is a full and exact description thereof.

My invention is intended for threading small metallic screws, sometimes denominated screw-nails, receiving the blanks previously prepared by other` machinery or'by hand.

My machine is necessarily complicated, but as many of the parts are similar to those heretofore in use, I will describe only the novel parts, with so much of the ordinary parts as is necessary to understand their relations thereto.

My improvements relate to the cutting of' screws having more than one thread. I prefer the form of thread described in the patent issued to Samuel Pratt, dated October 25, 1853. I prefer to make the screw's with three threads.

My machine provides for cutting the several threads separately, by repeating the operation of' bringing up the cutter and traversingit along the screw.

My machine cuts all the grooves slightly at irst, and afterwards deepens them.

Th'e accompanying drawings form a part of this specification.

Figure l is a front view, showing the novel parts of the machine.

Figure 2 is a plan View.

Figure 3 is a cross-section through the novel parts, on line S S in fig. 2.

Figure 4 is a horizontal section, showing more clearly the wedges which draw the tool rigidly and accurately to its work.

Figure 5 is a plan view, merely illustrating the mode of feeding forward the cutting-tool at each cut. This is not claimed as-rny invention.

Figure 6 is a vertical section, showing the same.

Similar letters of reference indicate like parts in all the figures.

Tints are employed merely to aid in distinguishing parts, and do not imply difference of material. The materials may be iron or steel.

Ais a rigid'frame-work, which may be of cast-iron,

which supports the several novel parte, as also the many ordinary parts not represented.

B` is an arbor, provided with suitable mechanism, not represented, for seizing and releasing a screw- It is supported in bearings inthe frame A, as represented, and is turned bya steam-engine or other power, not represented, in the direction indicated by the arrow.

It is enclosed by the bushing C, one end of which is enlarged, and forms a friction-pulley,as indicated by G. The motion which actuates the cutting-tool is transmitted through this bushing C.

Within the pulley is mounted alever-catch, D,turn ing on a centre, d, which is carried in the pulley C, and consequently rotates with the bushing C.

The arbor B is provided with three rectangular notches within the friction-pulley G, as indicated by bl la2 b3.

One end of the lever-catch D is adapted to .drop into and hold these notches, successively, one after the other, the other end of the lever-catch D projecting through a slot in the exterior of the friction-pulley Gl, with liberty to turn a little on the centre, (l.

There is a spring, E, carried within the frictionpulley C, which tends to hold the lever-catch D always fast in one of the notches b, b2, or b3.

WVhen, by contact with any suitable object, the levercatch D is tilted out of its hold in such notch, the arbor B is free to turn a portion of the revolution without giving a corresponding motion to the bushing O and its connections.

It is by this means that I change the position of the screw-blank, relatively to the threadingtool,`at short intervals, so as to cut three threads thereon.

It will be understood that the tool, and the means,-

for moving it longitudinally of the screw, are of the ordinary character, and may be operated by the aid of another shaft, mounted in a convenient position, and provided with the usual appliances.

Figs. 5 and 6 illustrate this, and will be brieily described.

T is the tool, T the tool-post or lever, and t a shaft turning therein, and holding the tool-post between collars, not represented.

This shaft is threaded at one portion of its length, and is free to move endwise, carrying the tool-post and tool with it.

The frame H forces the tool back to cut, through the medium of the`back-rest h, which presses against it.

H2 is a flame for bringing the back-rest-into line with the screw to be cut.

This turns upon pin H3, in frame H.

There are set-screws, H* and H5, in frame H, to regulate the back-rest.

The frame H, in moving back, forces the back-rest h,l in contact with tool-post T', thereby forcing the tool T upon'th-e screw M, to be cut.

As the tool reaches the part where the point should commence to taper oii, the tool-post T comes in contact with conical collar h2, which forces the tool T back further, thereby forming the point.

The forward motion of the frame H, and its connections, then allows the tool T to move away from the screw M, for the return movement.

.At this period one of the recesses in cam u comes i opposite the end of lever U', into which recess it falls,

thus liberating the half unt U from the screw on the shaft of tool-post T','and the latter is carried rapidly backto the place of beginning, by means of a spring, not represented.

The collar h2 is made to adjust, by sliding on the back-rest h, to suit length of screw, being fixed in the required position by a set-screw, h.

The tilting of the lever-catch D at the proper period is effected by means of the sliding-piece F, which is supportedon ways F', with liberty to slide.

There is a spiral spring, f, which tends to hold this slide always ont of use, but the latter is thrown into position, to act on the lever-catch D at. intervals, by mechanism which will be explained below.

The slide F is so formed, that when it is moved into position, to tilt the lever-catch D, it may press gently against the exterior of the friction-pulley C', and retard its motion, so as to insure the permanent disengagement of the catch from the arbor.

In other words, the tilting of the lever-catch D, to disengage it from the notches, is only for a very brief period, but it is suliicient to allow the arbor to get so much ahead of the bushing that when the lever-catch I) is again released it will not drop into the same notch, but will remain while the arbor B performs a third of a revolution, and will then catch into the next succeeding notch, after which the work will proceed as before, excepting that the screw-blank will be held in a different position, and the cutter or tool which cuts the met-al will acton it in a different spiral path, so as to form a separate groove or thread.

The friction of the piece F against the exterior' of' the friction-pulley C', tends to increase the certainty that the lever-catch D will not, on being released, drop back into the same notch from which it has just been lifted.

The gear-wheel O2, on the bushing C, acts, through the gearing Ca C* C, to give a correspondingly nearlycontinuous motion, but at a much-reduced speed, to the back shaft G, which is supported in bearings in the frame A, as represented, and turns in the direction indicated by the arrow.

G G are wipers, which give a motion, at intervals', t0 the slide F, above described; that is to say, the slide F is touched, by the points of the cams G G2, at proper intervals, and shifted into position to retard the bushing C, and its connections, a third of a revoluion, and is then released.

I have not deemed it necessary' to cucumber' this description with drawings of the cutter or chisel which forms the threads, nor ofthe ordinary approved mechanism by which it is moved rapidly forward as the screw-blank is turned.

It will be understood that the chisel is modified in form, according to the form of the thread required, and that it is traversed steadily along the screw-blank, in the same manner as in ordinary screw-machines, except that the mechanism is so proportioned and adjusted as to traverse it along faster than in ordinary machines; that is to say, the thread is quicker than in ordinary screws. So, also, the means by which the cutter is rrroved back, ont of contact with the screwthreads, for the back-traverse to resume its place after each cut, and prepare for another one, is very much like that ordinarily employed; but being intimately connected with my peculiar mechanism for bringing the cutter up to its place, to produce the requisite succession of cuts for each thread, I have represented, and will proceed to describe, some of the parts thereof.

The cutter, with parts of the mechanism for tmversing it, is carried on the framing H.

It is necessary, therefore, in order to describe all that relates to the bringing up of the cutter to its work, simply to describe the motions of the framing H.

This frame is supported at the front on bearings I I, which may be screws tapped through A, and is adapted to move ont and in thereon to the required extent.

The back part of' the frame H embraces a system of wedges, acting between it and a portion of the frame-work A'.

At the 'ont of the framing A is a spring, J, which tends to throw the framing H forward, and there is at the back au adjusting-screw, h, which bears against a. broad bearing-piece, H'.

It follows that the wedges or other operating-parts, by acting properly against the bearing-piece H', can control the position of the framing H, and consequently the critter which forms the threads.

There are two wedges contained within the framework A'. These two are differently operated, and are peculiarly adapted io each other, to give the right motion to the framing H.

One large wedge, K, is operated at regular intervals, and to a uniform extent. This wedge provides for the backward motion of the cutter after each traverse. This uniform motion is necessarily always sufficient to liberate the cutter entirely from the thread after the thread is fully cut.

The other wedge, L, is for graduating the depth of the cut, making, first, a slight cut for each thread, and afterwards repeating and deepening, till the full thread is formed.

The large wedge K bears fairly, by its front face, against the adjacent portions of the framing A', and bears fairly, by its back face, against a rectangular bar, L'.

The wedge K receives its regular reciprocating motion from a peculiar cam fixed on the shaft G, and acting on the pin or projection K', which extends backward and downward from the wedge K, as represented.

The cam is peculiarly formed, in two parts, adapted to act ou opposite sides of the pin K'.

Une part, G5, drives in the wedge, and holds it in steadily during a large part of cach revolution; but at the intervals when the cutter is to be moved back, recesses in this part of the cam become effective, and allow the wedge K to slide back.

The wedge K, being nicely fitted and lubricated, tends to slide ont, by the force of thc spring J and J'; but to insure this motion, I provide the parts G6 of the cam, which, acting on the pin or projection K', at the proper moment, compel the latter to enter the recesses in the cam G5. i

If the wedge K does not move back promptly, of itself, when liberated by the cam G, it iscornpelled to do so by the cam G. This makes a positive motion for this portion of the mechanism.

I will now describe the small wedge L, and its connections with the mechanism for imparting its peculiar motions.

It is lixed on the back of the rectangular bar L', which forms the back bearing for' the wedge K, as above intimated.

This bar L' is pressed gently forward by the pins a aa actuated by springs a a.

The pin l, inserted in the end of the bar L', as represented, is received in slots n, in a rod, N, which rod controls the position endwise, and gives, at proper intervals, a slight end-motion to thc bar L', without interfering with the side-motion thereof, received from the wedge K, as above described.

1n other words, the rod N constitutes an extension of the bar L', but without the side-motion thereof, the bar N being supported in a fixed bearing on the framework A, with liberty simply to move endwise.

This bar N is urged to the right by a spring, not represented, and it is moved to the left by the facecam acting on a pin, N', as represented.

This cam is formed in steps, Ol O' 0, corresponding to the depths to which the several cuts are made, in cutting the threads of the screw, and the cam being turned slowly, the width of the several steps is made sufficient to allow of the iirst three cuts at a. certain moderate depth, one cut foreach spiral groove. This is while the pin N rests on the part Oi of the cam.

Alter this, the part O2 of the cam comes into play, pressing the pin N', and consequently the wedge L, a little .further to the le, and holding it, there while three more cuts are made, one for each thread of the screw.

After this, the third and finishing-portion of the cam comes into play, and urges the pin N', and consequently the wedge L, a very little further to the left.

The means by which the peculiar cam, 0 02, 85e., is slowly rotated, will be readily understood from an inspection of the drawings.

The cams or teeth Gr3 G4 act, at intervals, on the wheel P, riving a` slow intermittent rotatory motion to this latter, as also to the connected wheel P'.

This latter wheel gears into the larger wheel Q, which latter is xed on the sleeve R, and thus turns the cam O O2, 85e., around intermittently, with a slow motion, exactly adapted to the purposes required.

It will be readilyunderstood that my invention can be employed to make screws with only two threads, instead of three, by employing only two of the notches b @distributed opposite to each other, or to make four, or' any other desired number of threads', by employing a corresponding number of notches.

It will be understood, that in such case the steps Ol 02, Ste., in the can which operates the rod N, are correspondingly increased or diminished in number.

Many modifications may be made in various other parts of the mechanism, without defeating the objects ofY my invention. Thus, for example, the back shaft G may be geared so as to revolve twice as rapidly as is here provided, and may, in such case, be correspondingly modified in the cams.

Having now fully described my invention,

What I claim as new, and desire to secure by Letters Patent, is as follows:

1. I claim the combination of the notched arbor B, spring-catch D, pulley G, tripping-wedge F, tappets Gl G2, and retracting-spring f, all arranged as and for the purposes set forth.

2. The described arrangement of the tripping-piece F, pulley G1, and spring-catch D, substantially as set forth.

3. I claim the cams G5 G, constructed as described, and arranged as shown, upon the shaft G, in combination with the projection K of wedge K, and the toolcarrier H and spring J', whereby said wedge is moved back and forth, by a positive motion, under all lconditions, as set forth.

4. I claim the relative arrangement ofthe wedge K, wedge-bar L L', bearing-block H', and tool-carrier H, substantially as herein set forth.

5. The shaft N, in combination with the cams O O2 O3, wedge-bar L L', and wedge K, the parts L N being connected by means of a pin working in a slot, whereby said wedge-bar L' is operated, both longitudinally and laterally, and the said motions are rendered independent of each other, substantially as herein described.

In testimony whereof, I have hereunto set my hand, in the presence of two subscribing witnesses.

NICHOLAS B. HADLEY.

Witnesses:

WM. B. HALE, WM. E. TURNER. 

